| 1 | /**
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| 2 | * \file lzma/delta.h
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| 3 | * \brief Delta filter
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Author: Lasse Collin
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| 8 | *
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| 9 | * This file has been put into the public domain.
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| 10 | * You can do whatever you want with this file.
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| 11 | *
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| 12 | * See ../lzma.h for information about liblzma as a whole.
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| 13 | */
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| 14 |
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| 15 | #ifndef LZMA_H_INTERNAL
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| 16 | # error Never include this file directly. Use <lzma.h> instead.
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| 17 | #endif
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| 18 |
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| 19 |
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| 20 | /**
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| 21 | * \brief Filter ID
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| 22 | *
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| 23 | * Filter ID of the Delta filter. This is used as lzma_filter.id.
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| 24 | */
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| 25 | #define LZMA_FILTER_DELTA LZMA_VLI_C(0x03)
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| 26 |
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| 27 |
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| 28 | /**
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| 29 | * \brief Type of the delta calculation
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| 30 | *
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| 31 | * Currently only byte-wise delta is supported. Other possible types could
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| 32 | * be, for example, delta of 16/32/64-bit little/big endian integers, but
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| 33 | * these are not currently planned since byte-wise delta is almost as good.
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| 34 | */
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| 35 | typedef enum {
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| 36 | LZMA_DELTA_TYPE_BYTE
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| 37 | } lzma_delta_type;
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| 38 |
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| 39 |
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| 40 | /**
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| 41 | * \brief Options for the Delta filter
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| 42 | *
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| 43 | * These options are needed by both encoder and decoder.
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| 44 | */
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| 45 | typedef struct {
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| 46 | /** For now, this must always be LZMA_DELTA_TYPE_BYTE. */
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| 47 | lzma_delta_type type;
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| 48 |
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| 49 | /**
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| 50 | * \brief Delta distance
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| 51 | *
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| 52 | * With the only currently supported type, LZMA_DELTA_TYPE_BYTE,
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| 53 | * the distance is as bytes.
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| 54 | *
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| 55 | * Examples:
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| 56 | * - 16-bit stereo audio: distance = 4 bytes
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| 57 | * - 24-bit RGB image data: distance = 3 bytes
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| 58 | */
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| 59 | uint32_t dist;
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| 60 | # define LZMA_DELTA_DIST_MIN 1
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| 61 | # define LZMA_DELTA_DIST_MAX 256
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| 62 |
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| 63 | /*
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| 64 | * Reserved space to allow possible future extensions without
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| 65 | * breaking the ABI. You should not touch these, because the names
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| 66 | * of these variables may change. These are and will never be used
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| 67 | * when type is LZMA_DELTA_TYPE_BYTE, so it is safe to leave these
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| 68 | * uninitialized.
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| 69 | */
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| 70 | uint32_t reserved_int1;
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| 71 | uint32_t reserved_int2;
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| 72 | uint32_t reserved_int3;
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| 73 | uint32_t reserved_int4;
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| 74 | void *reserved_ptr1;
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| 75 | void *reserved_ptr2;
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| 76 |
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| 77 | } lzma_options_delta;
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